Manchester United's Covid-19 outbreak has been revealed after Ralf Rangnick's sides clash with Brentford was postponed on Tuesday.The Red Devils had been forced to shut down their Carrington training bade 24 hours before the Premier League fixture.However, Carrington reopened on Wednesday as preparations continue for their Brighton clash, who are dealing with their own Covid outbreak.According to The Telegraph, United currently have 19 players and staff self-isolating, but not all are first-team related.This news comes after the Manchester Evening News reported that 17 first-team players were spotted arriving at Carrington on Wednesday morning.United's game against Brentford was the latest in a series of Premier League fixtures that have.